The Saturn’s Failing Plastic Window Parts

The driver’s side window on my Saturn SL2 sedan stopped working one day while I was out and about. When I got home, I took off the inside skin of the door to see what was wrong. The regulator arm was just hanging in space near the track at the bottom of the glass. I found the plastic piece that the regulator arm uses to lift the window -- it was in two pieces at the bottom of the door. I called the Saturn parts department to see if they had the plastic part in stock.

I was told the part wasn't sold separately and that the complete regulator was priced at $115. I needed the window to function so I went to the dealership and picked up the complete regulator. I mentioned to the guy at the parts counter that Saturn should offer the plastic part for sale. He agreed and told me a lot of people ask about getting just that part. I was able to install the regulator fairly quickly, since the plastic outer door panel is easily removed by unscrewing about seven plastic screws from the inside side of the door. This allows easy access to both sides of the inner workings of the door.

Later, when the passenger side window failed for the same reason, I took that door apart and removed the regulator so I could take it with me to compare it to the new one I was going to buy. When I was picking up the new regulator, I mentioned to a new guy at the parts counter that they should offer the plastic piece alone. He said they do.

Apparently, it has become a standard part due to the high number of failures and resulting requests. It was in stock at $7. What a deal. The ball joint on the end of the regulator arm is permanently attached to the arm, so I snapped the plastic piece on the ball with a large set of channel locks. I bought two of the plastic parts while I was there, so I was ready when the third one failed a year later. Shortly after that, a plastic part in the sun roof failed. Since a replacement sun roof is $1,700 -- and of course the broken part was not available à la carte -- it was time for a new vehicle.

This entry was submitted by John Zambito and edited by Jennifer Campbell.

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I have similar experience in my 1993 Suburban and of course my 1968 Pontiac (though the latter has very little plastic parts for operational items). I know plastic degrades over time. This is particularily true when exposed to UV. What gets me, is cars that are less than 10 years old and the plastic is breaking.

Back in the day (meaning when I was younger), I had a 1984 Oldsmobile with power seat. The motor for the seat was coupled to the track drive with a plastic coupler. The first time it broke, I thought maybe I was the fault as I am heavy and I probably was to much resistance for the coupler. $25 later and about 1 month it broke again! This time I asked the parts guy about it. He said they break all the time. This is a design feature! What? Yes, the plastic will break to prevent overloading the motor!

My point is, new cars are being built with more and more plastic to make them lighter for CAFE standards to be met. Service will evidently become part of the design feature. get out your wallet or plan on trading in the car every 5 to 10 years before the plastic gets brittle!

Wow, what an experience--but it's all too familiar now with the rampant use of plastic parts in automobiles. I am old enough to remember the days of chrome bumpers that would stay intact if you just nudged a wall or another car's bumper--now we have plastic ones that crumble or dent at the smallest impact. (Yes, I know I shouldn't be running into things, but it happens!) Plastic is on one hand one of the handiest inventions ever and also one of the most evil, in my opinion anyway. Yes it made things cheaper and lighter, but it's also taken its toll on quality and the environment.

All plastic is by no means created equal when it comes to strength and durability. The problem comes when lesser materials are spec'ed that will do the job, but won't do it long enough. But there are some places it should not be used at all. One of my favorite little desk clocks is now trash because it was made with, get this, plastic gears! And crummy cheapo plastic, at that. Of all the dumb things to use almost any plastic for, gears must be at the top of the list. Kind of like the brass gears in my old pretty but now useless hand coffee grinder: an equally dumb idea.

The author's experience reminds me of our driver door/window odyssey on my husband's (now departed) 1997 VW Jetta. We took it apart slowly over time--several weeks--to figure out what needed replacing where. It took so dang long because there was so much stuff on top of so much other stuff, and meanwhile, he had to drive it to work every day and secure the door somehow. That meant putting it back together every time after each disassembly.

I meant the Jetta was now departed, not my husband. He's still alive and kicking, and now fixing his latest used car, a Honda. Which, BTW, had a similar door/window problem on the driver's side, but didn't take nearly as long. Much saner design.

@Ann: Material selection is important, but part design is another big factor. Engineers who are designing plastic parts need to understand the properties of plastic materials. Don't assume that they deform linearly. Don't assume that they won't creep at room temperature. Don't assume that they will respond the same to a quickly-applied load as to a slowly-applied load. Don't assume that the properties are the same in every direction. Don't assume that the properties on the datasheet apply to anything other than a test bar.

I continue to refer people to an article that appeared in Design News nine years ago by Joseph Ogando titled The Misunderstood Material. It is a very good explanation of what plastic material properties actually mean.

Of course, Ann, you are right. It depends, as you said, what type of plastic is being used and what is being made of the material. Gears! Now that boggles the mind...even metal gears wear quite easily if they're not made quite durably! Yes, that was definitely a corner that could have been cut a different way. Still, I do miss chrome bumpers and other external car parts made of sturdier materials!

I read in another blog that the European car manufacturers (e.g. Mercedes) use biodegradable plastic to "save" the environment. After a few years, while the car is still in service, the parts start to degrade all on their own. So even if they survive the stress and strain of daily life, they will still fail early.

Leave it to the Europeans to come up with a planned obsolescence scheme that makes the old American GM/GE plans look amateurish.

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